The present invention is directed to a shape sensor and shape sensing device for detecting the shape of a moving strip of material. More particularly, the present invention is directed to a shape sensor and shape sensing device that can be used to detect a non-flat condition of a moving strip of material without the need to make contact therewith.
Strip (which may also be referred to herein as “sheet”) materials are used or produced in various industries. In at least certain of these industries, it is desired that a strip of material of interest have as flat a profile as possible. Unfortunately, it is also known that at least certain strip material manufacturing processes commonly impart one or more types of deformation to the strip materials produced thereby, which deformation tends to reduce the flatness of the strip materials. To that end, various devices, systems and techniques have been developed for both detecting and correcting the flatness of a moving strip of material.
While not limited thereto, a common use of such aforementioned flatness detecting and correcting devices, systems and techniques occurs in the production of strip metal products, wherein hot slabs or billets of steel and other metals are rolled into thin sheets. This hot-rolling process, as well as several devices, systems and techniques for detecting and/or correcting the flatness of sheet metal products produced thereby, is described in more detail in U.S. Pat. No. 6,857,301 (the '301 patent) to Bergman et al., which is hereby incorporated by reference herein.
As described in the '301 patent, hot-rolling mills typically produce sheet metals by using a series of rolls to exert a pressing force on a hot slab or billet that is passed beneath the rolls. However, exertion of a uniform pressing (flattening) force across the width of the strip is difficult. Consequently, finished strip materials often possess undesirable shape defects, such as a wavy edge(s) or a center buckle. These shape defects are generally the result of a non-uniform lengthwise stretching of the strip across its width. This non-uniform stretching produces stresses within the strip that lead to shape defects such as those recited above.
As also described in the '301 patent, microprocessor-controlled multi-roll levelers capable of automatically correcting for such shape defects in metal strip materials now exist. Shape defects in the strip materials may be detected and provided to these levelers by shape measurement devices. Both the air-bearing shape meter and displacement-type shape sensor described in the '301 patent are capable of detecting shape defects in moving strips of metal and other materials. Basically, an air-bearing shape meter operates to detect shape defects by sensing changes in the contact forces imparted thereto by a passing strip of material. A displacement-type shape sensor operates to detect shape defects by measuring an amount of linear displacement of a sensor(s) thereof afforded by a loose section of a strip of material passing overhead.
While both of the air-bearing shape meter and displacement-type shape sensor described in the '301 patent work quite well for most materials, it is nonetheless realized that there exist certain materials wherein the properties and/or final use thereof make it preferable to detect shape defects therein by a device/system that does not directly contact the material. A non-contact shape sensor and device of the present invention provides this ability.